EXPERIMENTAL CORROSION-MECHANICAL STUDIES OF WELL-DRYING EQUIPMENT IN THE OIL PRODUCTION INDUSTRY UNDER DYNAMIC LOAD IN AN AGGRESSIVE ENVIRONMENT

Abstract

In the first, comprehensive experimental studies of full-scale welded joints and steel structures under dynamic loading in the presence of a corrosive environment, in particular 5% saline solution and NACE - an environment according to the requirements of the International Association of Corrosion Engineers. The authors of this article developed a test bench scheme and worked out the expected modes of testing welded joints when programming the pressure and temperature of the environment and dynamic vibration modes. The test rig was manufactured jointly with specialists from the E.O. Paton Institute of Electric Welding of the National Academy of Sciences of Ukraine. All the main units of the rig are a hydropulsator, a thermal chamber, which included pipeline blocks with experimental welded joints, heating devices, a pneumatic control panel, a temperature and pressure control unit. The obtained experimental results made it possible to summarize, in particular: it was established that in the initial period (number of cycles N = 500) the crack growth rates in air and in 5% NaCl solution are close, and in the final period of testing they differ by more than an order of magnitude. Due to the more intense influence of the plane deformed state compared to the plane stressed state, the crack propagates in depth and only after germination over the entire thickness of the sample does its elongation begin. A significant reduction in the test period due to the introduction of a crack in the sample with a high stress concentration at the crack tip, which allows you to significantly reduce or modify the initial period. The possibility of detecting the sensitivity of materials to cracking, which is not detected when testing samples without a concentrator (for example, for pipe steels in seawater). However, the fracture mechanics method, like any other method, has a number of specific limitations on materials, thickness, and environments related to the correct use of fracture mechanics.